近50 a来辽河口水下三角洲演变特征研究

Evolution research on subaqueous delta of Liaohe Estuaryin recent 50years

本文基于近50 a来的辽河口海域的水下地形资料,采用GIS技术手段研究了辽河口水下三角洲的演变特征。研究结果表明:近50 a来辽河水下三角洲外缘(蛤蜊岗子滩西缘和南缘、西滩西缘和南缘)出现较大幅度的侵蚀后退;蛤蜊岗子滩东缘淤积外移,南部滩尾东部有北移东偏趋势;近岸浅滩由淤涨变为基本稳定,局部有所侵蚀后退;受蛤蜊岗子滩向东淤进的影响,蛤蜊岗子滩东侧深槽有所缩窄;蛤蜊岗子滩和西滩之间深槽水域出现拓宽变浅的变化趋势。流域来水来沙减少是近年来辽河口水下三角洲外缘侵蚀后退的主要原因,外缘侵蚀泥沙在波流作用下向河口搬运是蛤蜊岗子滩东侧淤积、深槽缩窄的主要原因,近岸边滩人工围垦对水下三角洲演变的影响值得关注。

Based on the topographical data of Liaohe Estuary in recent 50years,the subaqueous delta evolution of Liaohe Estuary was studied by using GIS methods.The research results are showed as follows:The outer edge of the subaqueous delta of Liaohe Estuary(the western and southern edges of Geligangzi Shoal,the western and southern edges of Xitan Shoal)experienced a relatively erosion progress and the eastern edges of Geligangzi Shoal experienced a accumulation progress and the eastern head of the southern part of Geligangzi Shoal had moved northward and eastward.The Nearshore Shoal between the two river mouths experienced a process from accumulation to stability,and the shoal had eroded partially north of East Trough.Because of Geligangzi Shoal moving eastward,East Trough at east of Geligangzi Shoal had became narrow,and the deep water between Geligangzi Shoal and Xitan Shoal appeared a trend of widening and becoming shallow.The decrease of incoming sediments from Liaohe River was the main cause for the erosion of the outer edges of the subaqueous delta.The erosive sediment transport up to the estuary under the action of wave and flow was the main cause for the siltation of east edge of Geligangzi Shoal and East Trough became shallow and narrow.The impact of the artificial reclamation of the nearshore beach on the evolution of the underwater delta was worthy of attention.